Gonorrhea is one of the most commonly reported infectious diseases in the United States and has increased substantially in recent years. The prevalence of gonorrhea, including pharyngeal gonorrhea is particularly high among men who report male sex partners. Between 2010 and 2017 the estimated rates of gonorrhea increased by 283% among men who report male sex partners, which was significantly higher than the 80% increase seen among other men in the United States. Oral (i.e., pharyngeal) infections with gonorrhea are thought to be a major driver of these increasing rates. Interventions to reduce pharyngeal gonorrhea have the potential for significant population impact on the overall incidence of gonorrhea. Preliminary data suggest a protective effect of commercially available mouthwash (antibacterial Listerine mouthwash) against pharyngeal gonorrhea. Given that mouthwash is widely available, easy to use, and relatively inexpensive it has the potential to serve as an important gonorrhea prevention strategy among a highly impacted population. However, further studies are needed to understand whether the inhibitory effects of mouthwash on overall bacterial load in the oral cavity translate to reduced risk of acquisition of pharyngeal gonorrhea. Therefore, the objectives of this study are to: (1) examine the acceptability of daily mouthwash use for the prevention of pharyngeal gonorrhea; and (2) measure the preliminary efficacy of daily use of antibacterial mouthwash as compared to a placebo mouthwash in reducing the incidence of pharyngeal gonorrhea among a cohort of high risk men. To accomplish this we propose to conduct a study that will leverage an existing cohort study designed to assess the epidemiological and immunological impact of substance use and HIV on minority men who have sex with men (mSTUDY). We will use a randomized crossover study design and participants in the proposed study will be those enrolled in the mSTUDY who have been previously diagnosed with pharyngeal gonorrhea. Half the participants will be randomized to first receive either the antibacterial mouthwash or the placebo mouthwash and all participants will be tested for pharyngeal gonorrhea at 12-weeks post intervention. At the 12-week mark participants will `crossover' to the alternative intervention group from which they were randomized at baseline. In this way, those assigned to the active mouthwash group will switch to the placebo mouthwash and vice versa and all participants will then be followed for another 12-weeks and will be tested for pharyngeal gonorrhea again after 12-weeks of cross-over intervention (i.e., 24 weeks following study enrollment). Findings from this study will contribute to our understanding of its potential acceptability and provide preliminary evidence of the efficacy of antibacterial mouthwash in preventing pharyngeal gonorrhea.